diff options
Diffstat (limited to '')
| -rw-r--r-- | vcl/README.GDIMetaFile | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/vcl/README.GDIMetaFile b/vcl/README.GDIMetaFile new file mode 100644 index 000000000..98be38d08 --- /dev/null +++ b/vcl/README.GDIMetaFile @@ -0,0 +1,190 @@ +GDIMetaFile class +================= + +The GDIMetaFile class reads, writes, manipulates and replays metafiles via the VCL module. + +A typical use case is to initialize a new GDIMetaFile, open the actual stored metafile and +read it in via GDIMetaFile::Read( aIStream ). This reads in the metafile into the GDIMetafile +object - it can read in an old-style VCLMTF metafile (back in the days that Microsoft didn't +document the metafile format this was used), as well as EMF+ files - and adds them to a list +(vector) of MetaActions. You can also populate your own GDIMetaFile via AddAction(), +RemoveAction(), ReplaceAction(), etc. + +Once the GDIMetafile object is read to be used, you can "play" the metafile, pause it, wind +forward or rewind the metafile. The metafile can be moved, scaled, rotated and clipped, as +well have the colours adjusted or replaced, or even made monochrome. + +The GDIMetafile can be used to get an OutputDevice's metafile via the Linker() and Record() +functions. + + +Using GDIMetafile +----------------- + +First, create a new GDIMetafile, this can be done via the default constructor. It can then +be constructed manually, or you can use Record() on an OutputDevice to populate the +GDIMetaFile, or of course you can read it from file with Read(). From here you can then +elect to manipulate the metafile, or play it back to another GDIMetafile or to an +OutputDevice via Play(). To store the file, use Write(). + +CONSTRUCTORS AND DESTRUCTORS + +- GDIMetaFile +- GDIMetaFile( cosnt GDIMetaFile& rMtf ) - copy constructor +- ~GDIMetaFile + + +OPERATORS + +- operator = +- operator == +- operator != + + +RECORDING AND PLAYBACK FUNCTIONS + +- Play(GDIMetaFile&, size_t) - play back metafile into another metafile up + to position +- Play(OutputDevice*, size_t) - play back metafile into OutputDevice up to + position +- Play(OutputDevice*, Point, Size, size_t) - play back metafile into OutputDevice at a + particular location on the OutputDevice, up + to the position in the metafile +- Pause - pauses or continues the playback +- IsPause +- Stop - stop playback fully +- WindStart - windback to start of the metafile +- windPrev - windback one record +- GetActionSize - get the number of records in the metafile + + +METAFILE RECORD FUNCTIONS + +- FirstAction - get the first metafile record +- NextAction - get the next metafile record from the + current position +- GetAction(size_t) - get the metafile record at location in file +- GetCurAction - get the current metafile record +- AddAction(MetaAction*) - appends a metafile record +- AddAction(MetaAction*, size_t) - adds a metafile record to a particular + location in the file +- RemoveAction - removes record at file location +- Clear - first stops if recording, then removes all + metafile records +- push_back - pushes back, basically a thin wrapper to the + metafile record list + + +READ AND WRITING + +- Read +- Write +- GetChecksum +- GetSizeBytes + + +DISPLACEMENT FUNCTIONS + +- Move( long nX, long nX) +- Move( long nX, long nX, long nDPIX, long nDPIY ) - Move method getting specifics how to + handle MapMode( MapUnit::MapPixel ) + + +TRANSFORMATION FUNCTIONS + +- Scale( double fScaleX, double fScaleY ) +- Scale( const Fraction& rScaleX, const Fraction& rScaleY ) +- Mirror +- Rotate( long nAngle10 ) +- Clip( const Rectangle& ) + + +COLOR ADJUSTMENT FUNCTIONS + +- Adjust - change luminance, contrast, gamma and RGB via a + percentage +- Convert - colour conversion +- ReplaceColors +- GetMonochromeMtf + + +Related classes +--------------- + +MetaAction: a base class used by all records. It implements a command-like pattern, and also +acts as a prototype for other actions. + + +CONSTRUCTORS AND DESTRUCTORS + +- MetaAction() - default constructor, sets mnRefCount to 1 and + mnType, in this case MetaActionType::NONE +- MetaAction(sal_uInt16 nType) - virtual constructor, sets mnType to nType, and + mnRefCount to 1 +- ~MetaAction + + +COMMAND FUNCTION + +- Execute(OutputDevice*) - execute the functionality of the record to the + OutputDevice. Part of command pattern. + + +FACTORY FUNCTION + +- Clone() - prototype clone function + + +MANIPULATION FUNCTIONS + +- Move(long nHorzMove, long nVerMove) +- Scale(double fScaleX, double fScaleY) + + +READ AND WRITE FUNCTIONS + +- Read +- Write +- ReadMetaAction - a static function, only used to determine which + MetaAction to call on to read the record, which + means that this is the function that must be used. + + +INTROSPECTIVE FUNCTIONS + +- GetType + + + +A note about MetaCommentAction: +------------------------------- + +So this class is the most interesting - a comment record is what is used to extended metafiles, to +make what we call an "Enhanced Metafile". This basically gets the OutputDevice's connect metafile +and adds the record via this when it runs Execute(). It doesn't actually do anything else, unlike +other MetaActions which invoke functions from OutputDevice. And if there is no connect metafile in +OutputDevice, then it just does nothing at all in Execute. Everything else works as normal (Read, +Write, etc). + + + +Basic pseudocode +---------------- + +The following illustrates an exceptionally basic and incomplete implementation of how to use +GDIMetafile. An example can be found at vcl/workben/mtfdemo.cxx + + +DemoWin::Paint() +{ + // assume that VCL has been initialized and a new application created + + Window* pWin = new WorkWindow(); + GDIMetaFile* pMtf = new GDIMetaFile(); + + SvFileStream aFileStream("example.emf", STEAM_READ); + + ReadWindowMetafile(aFileStream, pMtf); + pMtf->Play(pWin); + +} |